Early 120 front engine mounts

XK
1

I’ve read that on early RHD XK120s, Jaguar placed a couple of packing pieces under the right sandwich-type engine mount. This was to cant the engine over slightly to minimise clearance problems between the rear carb jet assembly and the steering column, especially if the 1/4" carb to manifold heat spacers were to be fitted.
At first, Jaguar did not use heat spacers at all, just a single gasket. This apparently resulted in severe fuel boiling due to heat transfer to the carb body and float bowl. I certainly found this to be the case with such an arrangement - the engine would surge mightily for 20-30 secs after a restart when hot. Things are a bit better now with a stack of several gaskets, but I’m planning to use 2 bottom plates from the old engine mounts under the new RH front mount. I’m assuming there will also need to be adjustment of the packing between the engine torque arm and its rubber buffer. Hopefully this will give me clearance for the 1/4" heat spacers.
Thoughts, anyone?
Chris

2

Before adding the 1/4 inch spacers, you should install a small under-dash shutoff switch for the fuel pump. On hot days when you know that fuel boiling will occur after engine shutoff, flip off the fuel pump switch 30 seconds before switching off the engine. This will leave the float bowls empty. When restarting the engine, flip on the switch and you will replenish the float bowls with cooler fuel and the engine should start and run normally.

You may find this completely solves the problem and avoids modifying the engine mounts and purchasing the eight longer manifold studs necessary to accommodate the thicker carb spacers.

3

Thanks for the tip, Mike.
My engine had the spacers before the recent engine rebuild, so the studs are already long enough. On a hot day when in heavy traffic I have noticed in the past that the engine starts to get more and more “fluffy” off-idle, which becomes a bit of a pain.
Of course, you have no such problems in the US, as your steering column is on the left side, so you can fit whatever thick carb spacers you like!